Method of forming a pile in situ



L. MULLER 3,512,365

5 Sheets-Sheet 1 METHOD OF FORMING A PI LE IN SITU ill I ll I n. u I I w I,

May 19, 1970 Original Filed Nov. 9, 1966 lnvenl or L\W\C mu. LL EL 'rvoasevs Hg. 70 (A -A) L. MULLER METHOD OF FORMING A 'PILE IN SITU Original Filed Nov. 9, 1966 May 19, 1970 5 sheets-sheet? Inventor 9 Lvamvb M LLLER.

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m m x-s L. MULLER METHOD OF FORMING A PILE IN SITU 3 E x 1 \mr/l/l/df/I /WW 7 i Jit a x 1 II 1/ vllllll'i May 19, 1970 Original Filed Nov. 9, 1966 United States Patent 3,512,365 METHOD OF FORMING A PILE IN SITU Ludwig Muller, 44-46 Heiurich-Heine-Strasse, 355 Marburg an der Lahn, Germany Original application Nov. 9, 1966, Ser. No. 593,139. Divided and this application Jan. 19, 1968, Ser. No. 721,900

Int. Cl. E02d 5/34 U.S. Cl. 61-5352 7 Claims ABSTRACT OF THE DISCLOSURE A construction pile is produced in situ. by driving a tubular shaft with an enlarged foot into the ground thereby forming an annular cavity about the shaft as the same is driven into the ground and gradually lowering a feed pipe into the cavity as the forming thereof progresses. The discharge end of the pipe is always kept close to the bottom of the cavity and the cavity is filled through the pipe from the bottom of the cavity upward with cementitious material thereby forming an outer pile layer. The shaft is thereupon withdrawn and the interior of the shaft while the same is being withdrawn is filled with a filler material thereby forming an inner core bonding itself to the outer pile layer.

This application is a divisional application divided out of my co-pending application 593,139 filed Nov. 9, 1966, now abandoned.

The present invention relates to a construction pile to be driven into the ground and anchored therein, and particularly to a construction pile to be produced in situ.

As is known, piles of the general kind above referred to can be produced in situ by driving a tubular shaft with a loosely attached pile foot into the ground. The shaft is then withdrawn and while being withdrawn is filled with concrete so that the filled-in concrete, which is tamped or compressed if necessary, is pressed against the surrounding soil strata. The surface friction of such pile and thus the anchoring thereof is comparatively low since the concrete does not key itself into the surrounding soil even if the concrete is pressed down or tamped. Such failure of the concrete to'key itself into the soil is primarily due to the fact that the concrete filled into the shaft is in a piece or granular form rather than in a flowable condition. In this connection, it should be pointed out that the term granular is not intended to indicate a specific size ofthe individual pieces of the concrete but merely to indicate that the concrete is not in flowable form.

Accordingly, the calculation of the load capacity of a pile of this kind must be based upon a low value of the friction between the wall of the pile and the surrounding soil.

It is an object of the present invention to provide a novel and improved construction pile of the general kind above referred to which when produced in situ is strongly keyed to the surrounding soil so that the load capacity of such pile is correspondingly increased by the high friction value between the soil and the Wall of the pile.

According to the invention the aforepointed out object, feature and advantage and other objects, features and advantages which will be pointed out hereinafter are obtained by providing a pile which when formed in situ has an outer layer formed by an initially flowable but hardened material and an inner core. This core can be produced by several different means and processes as will be more fully explained hereinafter. It is merely necessary that the core is capable of transmitting load and in particular pressure forces to the surrounding soil.

The outer layer being made of initially flowable and subsequently hardened material keys itself to the surrounding soil while it is still in flowable condition so that a high friction factor between the outer pile layer and the "surrounding soil is automatically obtained. As previously pointed out, such high friction factor is highly desirable when the load capacity of the pile is calculated.

The outer layer of the pile can be formed of flowable cementitious material or plastic and the core may be formed of a filler capable of being fed by dumping for instance, sand or a hardening mass in granulated or piece form such as concrete.

The core may also be in the form of a prefabricated column of steel or concrete. This column may be for instance in the form of a tube filled with a filler such as sand or a hardening mass.

Accordingly, a pile according to the invention comprises at least two layers which have a consistency dif ferent from each other at the time they are used to produce a pile in situ. The outer layer serves to key the pile to the surrounding soil and the core serves to transmit the load to the soil.

According to one exemplification of the invention a suitable method of producing a pile resides in driving a preferably tubular shaft into the ground and forming an annular cavity about the shaft while the same is being driven into the ground. The cavity surrounding the shaft is then filled with a suitable hardening material in flowable condition so that the material can penetrate into the.

pores or interstices of the soil. The flowable mass is preferably subjected to pressure while being fed into the cavity to increase the keying action of the mass. After the flowable mass is sufliciently hardened, the tubular shaft is gradually withdrawn and simultaneously or thereafter the space vacated by drawing of the shaft is filled with a filler to form the core. Finally, if necessary, the narrow annular space vacated by drawing of the shaft may also be filled with a flowable hardening mass so that the core is strongly joined to the surrounding outer layer. The tubular shaft can of course also be filled with core material while being driven.

The tubular shaft can also be surrounded by an outer sleeve while being driven. The aforementioned annular cavity is then formed about the outer sleeve. This cavity is filled with a flowable hardening material capable of keying itself to the surrounding soil strata whereupon the tubular shaft is withdrawn and a filler is fed into the sleeve which remains in the ground, either simultaneously with the withdrawal of the tubular shaft or upon completion of such withdrawal.

Another suitable method according to the invention resides in driving a tubular shaft into the ground while simultaneously forming an annular cavity about the tubular shaft. This cavity is filled with a flowable hardening mass and thereupon a pre-fabricated column is inserted into the tubular shaft. Finally, the shaft is withdrawn and the now vacant annular space between the column and the outer layer is filled simultaneously with the withdrawal of the shaft or thereafter.

The pre-fabricated column may be a tube made of steel or concrete and filled with a filler such as a hardening mass or sand.

Arrangements using a column which either encompasses the shaft or is disposed within the shaft, have the advantage that it is not necessary to dimension the column so that it is capable of sustaining the driving forces but merely so that it is capable of sustaining the static forces of the load upon the soil. Moreover, the same 3 tubular shaft can be used for several constructions of piles situ since it is re-covered after each use.

Obviously, a tubular shaft can also be driven into the soil while forming an annular cavity about the shaft which is thereupon filled with a flowable hardening mass to form the aforementioned outer layer. The tubular shaft is left in the ground and filled with a suitable filler so that the shaft itself constitutes the core or column of the pile.

As stated before, the cavity surrounding the tubular shaft is filled with flowable cementitious material or a hardening plastic mass. The use of a hardening plastic mass has the advantage that a pile having an outer layer made of hardened plastic can be safely used in aggressive water such as salt water. As is evident, the plastic layer protects the inner core and the tubular shaft against corrosion and other chemical attack.

The tubular shaft itself may be a steel tube, or a tube made of concrete or plastic.

The cavity formed about the tubular shaft can be filled with a flowable hardening mass while the shaft is being driven into the ground.

A suitable device for carrying out the method of the invention is for instance a tubular shaft which has at its lower end a foot, the peripheral outline of which is wider than the maximal peripheral outline of the shaft. The foot preferably ends in a wedge shaped portion to facilitate driving of the shaft. The foot may be fixedly or releasably secured to the shaft. A pile foot suitable for the purpose of the invention is shown for instance in prior Pats. 3,040,810, 3,054,268, 3,137,140 and 3,152,- 450 of the applicant herein.

The pile foot may also be inthe form of a collar fixedly or releasably secured to one end of the shaft and leaving said end uncovered. The outer wall of the collar is preferably inwardly tapered to form a wedge facilitating the driving of the shaft with the foot attached thereto. A foot fixedly secured to the shaft is preferably used when the tubular shaft is left in the ground.

When a tubular shaft with a foot or collar leaving uncovered the leading end of the shaft is driven into the ground, soil will naturally penetrate into the shaft and fill the same more or less. Upon completion of the driving operation, such soil can be removed by suitable means well known for the purpose if it be desired to fiil the shaft with a material other than soii.

One or several feed pipes may be lengthwise attached to the shaft to feed suitable flowable material into the cavity surrounding the shaft upon or during completion of the driving operation.

It is also suitable and within the concept of the invention to provide a tubular shaft which has lengthwise spaced openings in its wall, preferably extending down to the pile foot or collar. The flowabie material used for filling the cavity surrounding the shaft is then filled into the shaft itself and flows out through the openings into the cavity. A tubular shaft of this kind is preferably a centrifugally cast shaft Obviously, the tubular shaft and the core can be formed of several lengthwise aligned sections. The use of a sectionalized tubular shaft or core has the advantage that the driving equipment can be designed for a correspondingly lower load.

In the accompanying drawing several preferred embodiments of the invention are shown by way of illustration and not by way of limitation.

In the drawing:

FIG. la is a sectional elevational view of a tubular pile shaft with a loose foot;

FIG. 1b is a sectional view of the finished pile after withdrawal of the shaft, the foot being left in the ground;

FIG. is a section taken on line A-A of FIG. 1a;

FIG. 2a is a sectional elevational view of a modification of a tubular shaft a loose foot;

2b shows the completed pile, the foot being left in the ground;

FIG. 20 is a section taken on line BB of FIG. 2a;

FIG. 3a is an elevational sectional View of a tubular shaft with a foot in the form of a tapered collar fixedly secured to the shaft or integral therewith;

FIG. 3b is an elevational sectional view of the completed pile;

FIG. 30 is a section taken on line CC of FIG. 3a;

FIG. 4a is an elevational sectional. view of a further modification of a tubular shaft with a loose foot;

FIG. 4b is an elevational sectional view showing an intermediate stage of forming the pile in situ;

FIG. 4c is an elevational sectional view of the completed pile;

FIG. 5a is an elevational sectional view of a tubular shaft with a loose foot and an outer sleeve encompassing the shaft;

FIG. 5b is an elevational sectional view showing the outer sleeve after withdrawal of the tubular shaft; and

(FIG. 50 is an elevational sectional view of the completed pile.

Referring first to FIGS. 1a, lb and 1c more in detail, these figures show a tubular shaft 2 supporting at its leading end a foot 1 which has preferably a rectangular cross=section and the maximal peripheral outline of which is larger than the peripheral outline of shaft 2. An enlarged foot suitable for the purpose is fully described in the aforelisted prior patents of the applicant. Shaft 2 together with foot 1 are driven by suitable and conventional pile driving means into selected load carrying soil strata. Foot 1 due to its enlarged peripheral outline forms about shaft 2. an annular cavity when and while the shaft is being driven. This cavity is filled with a flowable hardening mass such as a cementitious material as the driving of the shaft progresses. The cementitious material may be fed into the cavity, preferably under pressure, through feed pipes 3a and 312. As is evident, the cementitious material gradually forms a jacket 4 about shaft 2 increasing upwardly from the bottom of the hole.

Pipes 3a and 35 may extend down to the foot, or they may terminate at a. selected level of shaft 2. They can be fixedly or exchangeably mounted on the shaft. Shaft 2 is with-drawn after the desired driving depth is reached and the cementitious material has sufficiently hardened.

The interior of the shaft 2 is filled with a suitable filler material such as concrete to form a core 6 of the pile. The concrete may be fed into shaft 2 after completion of the driving operation or during withdrawal of the shaft.

The annular space vacated by shaft 2 when the same is withdrawn, is also immediately filled with cementitious material preferably under pressure. Due to the filling of the annular space vacated by withdrawal of shaft 2, core 6 and the outer layer formed by jacket 4 are safely and strongly joined to each other.

The aforedescribed method of producing a pile in situ has the advantage that flowable hardening material such as cementitious material fed into the cavity formed about shaft 2 will penetrate into the pores or interstices of the surrounding soil strata 5 thereby strongly keying the jacket formed in the cavity to the surrounding soil. As is evident, the jacket increases the frietional force by which the fin ished pile is anchored in the ground.

According to FIGS. 2, 2b, and 20, a tubular shaft 12 has at its leading end a collar 11. The collar leaves uncovered the respective end of shaft 12 and has an inwardly tapered outer wall. The resulting wedge shape facilitates driving of the foot and the shaft. The peripheral outline of the collar is again larger than the peripheral outline of the shaft to form an annular cavity 8 about the shaft as the same is being driven.

Lengthwise pipes 9 serve to feed cementitious material into cavity 8.

As is evident, shaft 12 will be filled with soil during the driving operation. The soil may be removed by suitable means well known for the purpose so that the shaft can be filled with a suitable filler such as concrete or sand to form a core 13.

Obviously, a reinforcement such as a wire grid 14 may be inserted into the cylindrical space vacated when shaft 12 is withdrawn after jacket 8 has sufiiciently set. The foot is left in the ground.

According to FIGS. 3a, 3b and 3c, a tubular shaft 15 terminates at its leading end in a foot in the form of a generally wedge shaped collar 16. The wall of shaft 15 includes one or preferably several lengthwise ducts 17 which terminate, upwardly turned, in collar 16 as it is clearly shown. The ducts serve to feed a flowable hardening mass such as cementitious material into an annular cavity 18 formed by the action of the collar during the driving operation as previously explained. The jacket formed by the hardening cementitious material about shaft 15 keys itself to the surrounding soil strata, especially when the cementitious material is fed under pressure.

Shaft 15 being open at its leading end, is filled with soil 19 during the driving operation. Upon completion of this operation the soil is removed by means suitable for the purpose and the cylindrical space now vacated within the shaft is filled with a suitable filler 20 which forms the core of the pile. As can best be seen in FIG. 3b,

shaft 15 remains in the ground and thus becomes part of.

the core.

FIGS. 4a, 4b and 40 show a pile structure in which a tubular shaft 21 releasably mounting a foot 22 is driven into the ground. The foot again has a peripheral outline wider than the maximal peripheral outline of shaft 21 to form a cavity 23 surrounding shaft 21 when the same is driven into the ground. The cavity is filled with a cementitious material or other suitable hardening material by one or several feed pipes 24 mounted on the outside of the shaft to form the outer layer or jacket of the ile. P Upon completion of the driving of the shaft and filling of cavity 23, a pre-fabricated column 25 is inserted into shaft 21. Thereupon shaft 21 is withdrawn and the annular space formed between the jacket and column 26 is simultaneously or shortly thereafter filled with cementitious material to join column 25 to the jacket. Column 25 can be solid or be hollow. If hollow, it is filled with a suitable filler such as concrete or sand as is indicated in FIG. 411.

According to FIGS. 51:, 5b and 50, a tubular shaft 27 together with an outer sleeve 28 closely jacketing the shaft is driven into the ground by applying the driving force to the shaft. The enlarged head 1 at the leading end of shaft 27 and the sleeve 28 form a cavity about sleeve 28. This cavity is filled with cementitious material or other flowable material by means of a hose 29' detachably secured to the outside of shaft 27 and extended close to foot 1.

Sleeve 28 may be fixedly secured to foot 1 or may loosely rest upon the same.

When the required driving depth is reached shaft 27 is withdrawn and the interior of sleeve 28 is filled with a suitable filler 31. As is evident, the core is formed by the filler material in the sleeve 28.

When a loose pile foot is used, the interior of the pile shaft or the sleeve is sealed at the pile foot against the cavity formed about the shaft or the sleeve.

Finally, it may be mentioned that in all the illustrated exemplifications of the invention the cavity formed by foot 1 during the driving operation may be filled by a hose extended from the top into the cavity as the same is being formed.

While the invention has been described in detail with respect to certain now preferred examples and embodiments of the invention, it will be understood by those skilled in the art, after understanding the invention, that various changes and modifications may be made without departing from the spirit and scope of the invention, and it is intended, therefore, to cover all such changes and modifications in the appended claims.

What is claimed is:

1. A method of producing a construction pile in situ, said method comprising the steps of: driving a tubular shaft having an enlarged foot at its leading end into a ground stratum thereby forming an annular cavity about the shaft as the same is driven into the ground; lowering a feed pipe into the cavity as the forming thereof progresses with the discharge end of the pipe always kept close to the bottom of the cavity; filling said cavity through said pipe from the bottom upward with a flowable hardening material to form an outer pile layer; withdrawing said shaft after filling the cavity; and filling the interior of the shaft with a filler material when and while the shaft is being withdrawn to form an inner core bonded to the outer layer in the space vacated by the shaft.

2. The method according to claim 1, wherein the flowable hardening material is fed into the cavity under pressure to key the material to the surrounding ground.

3. The method according to claim 1, wherein the flowable hardening material is simultaneously fed into the annular cavity formed about the shaft and into the space vacated within the shaft as the same is withdrawn thereby bonding together the matreial fed into the cavity and the material fed into the space vacated by withdrawal of the shaft.

4. A method of producing a construction pile in situ, said method comprising the steps of: providing a tubular shaft having an enlarged foot at its leading end and a sleeve closely jacketing said shaft; driving the shaft together with the sleeve into a ground stratum by applying a driving force to the shaft only thereby forming an annular cavity about the shaft and the sleeve as the same are driven into the ground; lowering a feed pipe into the cavity as the forming thereof progresses with the discharge end of the pipe always kept close to the bottom of the cavity; filling said cavity through said pipe from the bottom upward with a flowable hardening material to form an outer pile layer; withdrawing said tubular shaft while leaving the sleeve in the ground; and filling the space vacated by the shaft and defined by the sleeve with a filler material.

5. A method of producing a construction pile in situ, said method comprising the steps of: driving a tubular shaft having an enlarged foot at its leading end into a ground stratum thereby forming an annular cavity about the shaft as the same is being driven into the ground stratum; lowering a feed pipe into the cavity as the forming thereof progresses with the discharge end of the pipe always close to the bottom of the cavity; filling said cavity through said pipe from the bottom upward with a flowable hardening material to form an outer pile layer; inserting a preformed column into the interior of the tubular shaft; withdrawing the shaft; and filling the annular space vacated by the shaft between the outer layer and the column with a flowable hardening material.

6. The method according to claim 5, wherein said annular space is filled While the shaft is being withdrawn.

7. A method of producing a construction pile in situ, said method comprising the steps of: driving a tubular shaft open at its leading end and having an enlarged collar like foot at the leading end into a load carrying ground stratum thereby forming an annular cavity about the shaft as the sameis being driven; removing ground stratum accumulated within the shaft during the driving thereof; lowering a feed pipe into the cavity as the forming thereof progresses with the discharge end of the pipe always kept close to the bottom of the cavity; filling said cavity through said pipe from the bottom upward with a flowable hardening material to form an outer pile layer;

8 and filling the space vacated within the shaft simultaneous FOREIGN PATENTS with the cavity with a filler material to form a core in 816,086 4/1937 France 521d space- 521,684 5/1940 Great Britain.

References Cited 5 JACOB SHAPIRO, Pnmary Examlner UNITED STATES PATENTS 1,275,470 8/1918 Pruyn 6153.66 X 3,206,935 9/1965 Phares 61s3.52 61-5356, 53.58, 53.62, 53.64, 53.66, 53.74 

